Process of and product for attaching portions of molds or cores



Patented Feb. 14, 1933 UNITED STATES PATENT OFFICE CHARLES MARSHALLSAEGEB, JR OF IBOWMANSTOWN, PENNSYLVANIA PROCESS OF AND PRODUCT FOB A'ITAOH ING PORTIONS OF HOLDS OB CORES K Drawing.

Application filed February 17, 1980; Serial in. 429,223.

(GRANTED mun run nor or'mcna, less, as mmmn 4mm. so, 1928; 870 o. c.757) My inventionrelates to a new and useful process of, and productfor, attaching portions to molds or cores for the production of castingsof molten steel, iron, brass, alumi- 5 mum and the like high meltingpoint metals where the molds or cores are formed of sand or otherrefractory particles molded to the form to produce the desired shape ofthe casting. v

Heretofore in this art, cores have been formed in the portions, forinstance, in halves, as the most convenient and economical means lortheir production, and such halves have been secured together by a pastewhich has heretofore been formed either of flour and water or molassesdiluted with some water. Likewise, portions have been attached to moldswith or without the employment of a wire or other anchor and'with suchpaste ac to both'seal the joint as well as aid in such attachment. Thewater content of such past-e, as well as the water content of such pastethat has been imparted to the mold or core to which the same has beenapplied, not removable therefromexcept by'the ap plication thereto of asubstantial heat for a protracted period which results in the for--mation of an indurated or haked mold or core which will not ordinarilyyield readily ac to the shrinkage of the casting, and which has resultedin many cracked or shrinkage; severed castings, and which also tends toproduce a mold or core of such lessened permeability that the asesformed by the heat action or, reaction 0% the metal casting therein withthe mold or core constituents are not readily escapable through thematerial comprising sucl mold or core and which occasions substantialcasting loss, due to what is as commonly known as blows, that is, thepressure of the gas commingling with the fluid metal results in acasting which is defective due to its containing substantial voids.

Gonsequently, it has heretofore been the practice to emplo molds orcores which, through the application of said paste or otherwise, have asubstantial water content at the time when the cast metal is castagainst the surfaces of such molds and cores. The head of the liquidmetal vaporizes such y'ater content relatively slowly and fills thecavity char-ring of the organic substances on the mold ,and coresurfaces, thus causing contact of said oxidized surfaces of the castmetal with the uncoated or uninsulated particles of the mold or core,and which results in'the fusion, embedding into, or adherence of saidparticles to thesurfaces' of the casting. This action also leaves asubstantial oxygen con tent, residual from the air, in the castingcavity of the molds whichis-being filled with the hot liquid metal, andwhich oxygen also promotes oxidation of the metal surfaces and theremoval of the char from'the mold or core surfaces, thus contributing-tosuch fusing of, and adherence to the casting surfaces.

This resultsin the outer surface or sur- 7 faces of the castings beingformed of an integral, fused, or commingled layer of metal and sandorother constituent ofthe mold or core, which produces a casting ofpoor' appearance as well as 'one, whose surfaces, 7 which are requiredto he machined, quickly remove the edge from the machine cutting toolsunless a suficient amount of surplus metal is cast upon such surfaces inorder to, enable the machining tools at their first cut 30 to penetratebelow the area of such fused or commingled surfaces.

My present invention is a continuation in part of my co-pendingapplications, Serial Nos. 332,225 and 332,226, and of my companionapplication executed on the same date herewith. In my said applicationsthe materials therein stated are either added to and intimately mixedwith the molding sand or are coated upon the exterior surfaces of themold and/or core which come in contact with the casting. I have foundthat the molds and/ or cores so made which have their several partspasted together with the core paste of l the rior art are liable to, anddo, result in a num er of bad castings due to such core paste of theprior art producing a substantial gaseous or. other reaction, activatedby the heat of the cast metal. This has required substantialinvestigation and research to ascertain both the cause and the remedyfor such casting failures and which contributed to the resent inventionwhich is the development in fact of an improved new and useful corepaste.

In theproducton of my vnew and useful im roved core paste, I employ anyof the materials of rubber, rubber-like or plastic characteristicsdescribedin my aforesaid co-pending applications. Such material is mixedwith a solvent or with water or other liquid; according to thewell-known plasticizing characteristics of the material employed, toobtain the desired consistency of the paste. This consistency isdetermined by the size and weight of the parts of the core or mold tobe'therewith'cemented together, since a relatively thin'and/or weakadhesive is capable of satisfactorily joining light portions while athicker and/or stronger adhesive mixture is required to satisfactorilycement together heavier portions.

This paste may then be applied to either or both of the surfaces to becemented together and then suchportions juxtaposed.

Where such aste is naturally adhesive in the condition m which it is soapplied the parts are satisfactorily cemented together by the naturalprocess arising between the time such surfaces are juxtaposed and themaking of the casting. In cases where such paste ingradient ormgredients are not substantially adhesive in the state in which thepaste is so applied, as well as where a stronger cementing of the joinedparts is required an atmospheric or a higher temperature vulcanizingaccelerant of any of the well-known kinds should be added to the degreewell-known to produce the required result, and the cemented core and/ormold subjected, before being used in making castings, to the atmosphericor high temperature required to produce the desired vulcanization.

While the ingredients of my core paste are higher in price than the corepastes of the prior art, yet the superior advantages it at tains renderhighly economic the use of my core paste.-

The rubber or rubber-like content of my core paste is present thereinincidentally for 1 its known adhesive property and is employed primarilyfor the heat reaction forded to the molding sand an to the surface ofthe casting by the heat of such castin while coolin in the sand core ormold w ose parts may joined bymy said paste. This heat reactionevidences the property unexpected of adhesives of maintaining suflicient adhesive strength to hold the core parts in their fixed positionsuntil the casting formed by the core has cooled sufiiciently to becomenon-fluid. Thereafter the adhesive property is destroyed by theconstituents of my core paste being combusted by the arbotracted heat ofthe cooling casting. e

(property affilm prevents the sand or other components of 'the mold orcore from adhering to or becoming imbedded in the surface of thecasting.

Said products also permeate the mold or core and render the constituentsreadily separable from the casting and from each other and enables thecore sand to be reusable for the making of other cores withoutregranulation or other similar labor.

. With molds and/or cores made in accordance with either of my aforesaidco-pending a plications by having their cemented port ons joinedtogether with core pa$e of the prior art, and where a usable castingresults therefrom, the portions of such castings made in contact withthe joint or joints formed by the core paste of the priorart, aresubstantially harder than the other portions of the casting and/or haveembedded therein or adherin thereto a scale. Such portions of thecastlng at, and adjacent to, the exterior edges of the mold and/or coreportions cemented together with the core paste of the prior art aresubstantially harder than the other portions of the casting due to themore rapid cooling of the metal at such points. This more rapid coolingchanges the characteristic of the metal at such points and sets upstresses therein and between such hardened and the adjoinin normalmetal. This results in castings hig y unsatisfactory for many normal andpractically all exacting conditions. Where such surfaces are required tobe machined the cutting tool or tools ,are forced to cut, for instance,continuously in alternating areas of normally soft metal as well asthrough intermediate areas of substantially harder or unduly hard metal,

which with or without the said scale, are associated withsaid hardermetal, creates undue strains upon the cutting tools and/or upon themachine which are desirable'to avoid in efficient economical production.

This is but one typical of the many substantial advantages attained bythe use of my present invention.

Reference may be had to my aforesaid copending applications. in anyrespects that ma be desired for a fuller discussion and/or un erstandinof the ingredients of 'my said core aste an /or the action or reactionarising om their contact with the material to be cast in the mold and/orcore cemented with my core paste. k

The term rubber-like substance will be understood by. those skilled inthe art of metal casting and foundry practice as any substance ormixture which affords in or on The invention herein described may bemanufactured and used by or for the Government of the United States forgovernmental purposes without the payment to me of any royalty thereonor therefor.

Having now so fully described my invention that others skilled in theart may therefrom make and use the same, what I claim and desire tosecure by Letters Patent is:

1. The method of joining together separate portion of a mold or core forthe making of castings of molten steel, iron, brass, aluminum and thelike high melting point metals, including the step of placing betweensuch portions a substance containing rubber adapted to be juxtaposed toand subjected to disintegration by the heat of the cast metal.

2. The method of joining together separate portions of a mold or corefor the making of castings of molten steel, iron, brass, aluminum andthe like highimelting point metals, including the step of placingbetween such portions a plastic derivative of rubber adapted to bejuxtaposed to and subjected to disintegration by the heat of the castmetal.

3. The method of joining together separate portions of a mold or corefor the making of castings of molten steel, iron, brass, aluminum andthe like high melting point metals, including the steps of placingbetween such portions a substance containing rubber and vulcanizing thesame before using such mold or core, said rubber being'adapted to bejuxtaposed to and subjected to disintegration by the heat of the castmetal.

4. The method of joining together separate portions of a mold or corefor the making of castings of molten steel, iron, brass, aluminum andthe like high melting point metals, including the steps of placingbetween such portions a plastic derivative of rubber and vulcanizing thesame before usin such mold or core, said rubber being adapte to bejuxtaposed to and subjected to disintegration by the heat of the castmetal.

5. A core paste for cores for the making of castings of molten steel,iron, brass, aluminum and the like high melting point metals, said pastecontaining rubber.

6. A core paste for cores for the making of castings of molten steel,iron, brass, aluminum and the like high melting point metals, said pastecontaining a heat-plastic selected from the class comprisingsubstantially rubher and rubber components adapted to maintainadhesiveness until the casting has become non-fluid and to be combustedby the protracted heat of the cooling casting, which combustion rendersthe core component reusable for the making of further cores.

7. A core paste for cores for the making of castings of molten steel.iron, brass, alumi num and the like high melting point metals,

- said paste containing a plastic derivative of rubber adapted to besubjected to disintegration by the heat of the cast metal.

8. A core paste for cores for the making of castings of molten steel,brass, aluminum and the like high melting point metals, said pastecontaining rubber and a vulcanizing accelerant, said rubber beingadaptedto be subjected to disintegration by the heat of the cast metal.

9. A core paste for cores for the making of castings of molten steel,brass, aluminum and the like high melting point metals, said pastecontaining a plastic derivative of rubber and a'drying accelerant, saidrubber being adapted to be subjected to disintegration by the heat ofthecast metal.

CHARLES MARSHALL SAEGER, Jr.

